Method for producing aqueous liquor dyeable modified polypropylene threads and the use thereof

ABSTRACT

The invention relates to a method for producing aqueous liquor dyeable modified polypropylene threads. The inventive method is characterized in that a CR polypropylene suitable for fiber formation is mixed with a reaction partner which can react with CR polypropylene and the mixture obtained is processed in an extrusion spinning facility to form a thread. Suitable reaction partners are difunctional carboxylic acids, corresponding carboxylic acid derivatives or master batches made of polypropylene and difunctional carboxylic acids or corresponding carboxylic acid derivatives. The polypropylene threads obtained can be knitted to form textile fabrics. The polypropylene threads and textile fabrics can be dyed with the usual coloring agents according to a standard aqueous liquor extrusion process.

This application is the National Phase under 35 U.S.C. §371 ofInternational Application PCT/EP98/06700 filed Oct. 22, 1998.

FIELD OF INVENTION

The invention concerns a method for producing aqueous liquor dyeablemodified polypropylene threads, the polypropylene threads obtained withsaid method as well as the utilization of polypropylene threads for themanufacture of flat textile shapes. The invention concerns also a methodfor dyeing polypropylene threads and/or the textile shapes.

It is a known fact that it is difficult to dye unmodified polypropyleneinasmuch as it can enter only into fragile Vander Waals interactionswith a dyestuff molecule, based on its homopolar structure.

In order to nevertheless be able to dye polypropylene, the followingdyeing methods are commercially employed at the present time.

According to one method, the threads are spin-dyed in that during theextrusion process a colored master batch granulate is used, which isprepared from a polypropylene type suitable for fiber formation and asuitable color pigment. While deep color tints are obtained with thismethod, the flexibility is low and productivity is limited inasmuch asthe rinsing cycles required for any change in color and/or the resultingcolor mixtures permit only few color changes for reasons of economy.

Based on the rapidly changing, fashion-oriented color guidelines,however, more flexibility is desired at the present time. If the earliermentioned so-called batch coloring mode is not desirable, it is alsocustomary to achieve, for example by addition of nickelous salts to thepolymer melt, an improved color acceptance capability of the polymerthreads from an aqueous dye bath in that subsequently metallic compounddyes are employed in the aqueous bath dyeing process. This method,however, raises concerns due to ecological reasons because of theadditions of heavy metal.

These two popular methods for dyeing polypropylene threads are describedin M. Ahmed, Polypropylene Fibers—Science and Technology, ElsevierPublishing House, Amsterdam 1982.

Proceeding from the above described state of the art, it is the objectof the present invention to make available a method for the productionof modified polypropylene threads, which after standard extrusion methodfrom an aqueous dye bath can be dyed with deep color tints of greatintensity.

Said dyeing is to be achieve with commercially obtainable dyeing agents,using customary concentrations of dye. This method, in addition, shallhave as few process steps as possible, thus resulting in cost savingsand shall also be completely harmless ecologically.

According to the invention, said object is solved by a method which ischaracterized in that CR-polypropylene suitable for fiber formation ismixed with a reaction partner that can react with the CR-polypropyleneand the obtained mixture is processed into threads in anextrusion-spinning fixture.

The term CR-polypropylene means a polypropylene type with controlledflow behavior (CR=controlled rheology). The controlled flow behavior canbe obtained can be obtained by various routes, for example bymechanical-thermal, γ-radiation, oxidation or by addition of peroxides.The most frequently employed method consists in that organic peroxidesare added to the powdery polymer during the preparatory or processingstep. Free radicals are formed in the heat, which preferably split offhydrogen from the statistically predominating longest hydrogen chains,resulting, via subsequent reactions, in chain splittings and thusproduce a denser mol mass distribution, resulting in a higher meltindex. The easy flowing CR-polypropylene thus contains, like any otherthermal oxidatively stressed polypropylene type, hydroxyl groups. Theseoccur in the named polypropylene types as forcibly produced end or sidegroups.

The melting index MFR (melt flow rate at 2.16 kg/10 min) of the employedCR-polypropylene lies in the range of approximately 10 to 1200. The meltindex preferably lies in the range of approximately 15 to 300,particularly preferred is a range of approximately 20 to 120. Themolecular weight of the employed CR-polypropylene therefore lies in therange of approximately 300,000 to 80,000, preferably in the range ofapproximately 250,000 to 110,000 and particularly preferred in the rangeof approximately 220,000 to 130,000.

It is of critical importance to select the reaction partner in suchmanner that same can react via its functional groups withCR-polypropylene, for example, cumulatively or via a substitutereaction. Consequently, permanent functionality is produced in theCR-polypropylene. Said functionality is then utilized in that during thedyeing in an aqueous dye bath, the respective dye substances react, inaccordance with their interaction potentials, with the functional groupsand thus produce intense and permanent color hues of the polypropylenethread. It is only due to said subsequent installation according to theinvention of reactive groups in the polypropylene chain that therequired anchoring groups are available, which are able by other thanVan der Waals compounds, for example, ionic or co-valent bindingmechanisms, to interact in stronger measure with the respective coloringagents, which thus make possible more intense color tints.

According to the invention, CR-propylene, suitable for formation offibers, is processed jointly with a certain reaction partner, as aresult of which the needed prerequisites are created during extrusionand in fiber formation, that in a future dyeing process an employedcoloring substance can be applied from an aqueous dye bath and,furthermore, that it will possess satisfactory adhesive property. Indifference to subsequent grafting methods, which may result inmodifications of the same kind, in accordance with the method accordingto the invention, no separate and consequently expensive processing stepis needed. The invention thus not only opens up a cost-effective method,but also affords access to a hitherto barely reachable market which isdetermined by rapidly changing, fashion-oriented color trends. Anotherbenefit of the invention lies in the fact that the CR-polypropylene canbe employed relatively independently from its molecular weight and itsmolecular weight distribution.

It is of particular benefit to employ as reaction partner a difunctionalcarboxylic acid or a corresponding carboxylic acid derivative,specifically a carboxylic acid ester, a carboxylic acid anhydride, acarboxylic acid amide, a carboxylic acid imide, a carboxylic acidhalogenide or a carboxylic acid nitrile. Based on their chemicalstructures, these compounds are particularly well suited for enteringinto a reaction with the polypropylene.

It is particularly beneficial to employ as reaction partner a masterbatch of polypropylene and a difunctional carboxylic acid or acorresponding carboxylic acid derivative. The utilization of this kindof master batch has the advantage that the preparation of the mixture ofmaster batch and CR-polypropylene is particularly simple.

The reaction partner is employed in a quantity of up to approximately12% by weight, preferably up to approximately 3% by weight, andspecifically up to approximately 1% by weight. The lower the employedquantity of the reaction partner, the more cost effective the method.

When implementing the method according to the invention, it may be ofbenefit for accelerating the reaction to employ a peroxidic addition asreaction initiator. The initiator employed in customary quantities,whereby its weight percentage concentration lies lower by approximatelythe power of ten than that of the reaction partner. Inorganic andorganic peroxides, such as for example 2.5di-methyl-2,5-bis-(t.butylperoxy-hexane) have proven themselves asparticularly suitable reaction initiators.

Mixing of the CR-polypropylene with the reaction partner is most simplydone by mechanical method. In order to attain a homogenous distributionof the reaction partner and, if applicable, also of the reactioninitiators in the polypropylene, it is of benefit to extensively mix thereaction mixture. This homogenous distribution is facilitated by the useof master batches.

For execution of the method, customary extrusion-spinning facilities areused. It is, however, of benefit if the extruder is equipped withdynamic and/or static mixing elements, since this realized furtherhomogenization of the melt.

The extrusion and winding conditions of thread manufacturing lie withinthe scope of the usual values for the production of LOY and/or POYmaterials. It is, however, also possible, to exceed the traditionalprocessing temperatures of polypropylene as a function of the meltingpoint of the reaction partner. Mass temperatures in theextrusion/spinning facility of approximately 230 to 300° C. have provento be particularly beneficial. As for the nozzle hole numbers (forexample 13-22 hole) and the nozzle geometry (for example holediameter=250 μm). The spinning nozzles also operate with conventionalmeasurements, by means of which are preferably produced spin threadtiters in the range of approximately 60-600 dtex and/or filament titersof approximately 5-15 dtex. With respect to preferred spin velocities inthe range of approximately 300-3000 m/min, the spun filament threadspossess residual expansion values on the order of 200-700%. Thisresults, relative to any subsequent stretching procedure in order toreach a final elongation of approximately 25%, using applicablestretching ratios of approximately 1:6.4 to 1:2.4, in filamentstretching titer of preferably approximately 2.5-3.2 dtex. Theresistance to tearing obtained in the stretched filament threads lies inthe range of approximately 50-60 cN/tex and thus is no different fromthreads that were produced from unmodified polypropylene.

The threads according to the invention can be further processed, subjectto the customary conditions, into flat textile shapes, preferably intoknitted fabrics.

Further object of the present invention is a method for dyeing thepolypropylene threads and flat textile shapes according to theinvention. As mentioned earlier, the polypropylene threads according tothe invention and the flat textile shapes according to the invention canbe dyed in simple fashion according to a standard extrusion method in anaqueous dye bath. It is possible using traditional coloring agentconcentrations, proportionate to the product weight, to achieve shadesof color with extremely high intensity. Almost any type of coloringsubstance can be used which is able to react, according to theinvention, via its own functional groups with the polypropylene threadsor the flat shapes. This results not only in an intense color shade butalso in permanent coloring.

Acid dyes, dispersion dyes and reactive dyes as well cationic dyes haveproven themselves as particularly suitable. When utilizing these dyes,it is possible to maintain the coloring specifications listed in thecolor charts issued by the dye manufacturers.

Lastly, in certain instances it may be a benefit to establish conditionsrelative to pH value, dyeing temperature and dyeing duration whichdiffer from the conditions recommended by the manufacturers. It ispossible to select pH values from strongly acid to strongly alkaline andhigh dyeing temperatures, even as high as approximately 135° C., inother words HT conditions. It is possible to increase the dyeing time toup to about 2 hours.

In addition, it is possible to employ other dyeing adjuvants, such asfor example ionic and non-ionic wetting agents, dispersion agents,scooping agents, antistatic and equalizing agents as well as retardingagents.

Depending upon the employed dye type and its concentration, it ispossible to obtain highly intensive color shades. The remission valuesof the dyed samples, measured at the absorption maximum, may clearly bebelow the 2% mark, which corresponds to K/S values in excess of 30. Theone hour after treatment in tenside containing bath at boilingtemperature, performed after the dyeing steps, which results in a barelyvisible coloration of the rinsing water, attests to excellent adhesiveproperty of the dyes to the substrates.

In the following, the invention is explained in greater detail.

EXAMPLE 1

Commercial CR-polypropylene granulate for fiber application having amelt index of MFR-25 (melt flowrate, at 2.16 kg/10)—obtainable fromHoechst AG under the trade name Hostalen PPU 1780F1—is mechanicallymixed with powdery pyro-mellitic acid-dianhydride in such manner thatthe percentage of the pyro-mellitic acid-dianhydride in the mixturetotals 0.5% by weight. Said mixture is fed into the extrusion/spinningfacility and processed into filament threads at a mass temperature of285° C.

EXAMPLES 2 and 3

Granulate mixtures as described in Example 1, except for a mixingpercentage of 1 or 3 percent by weight are processed into filamentthreads, under the same conditions as in Example 1.

EXAMPLE 4

Commercial CR-polypropylene granulate as described in example 1 is mixedwith a master batch of polypropylene and maleic acid anhydride,obtainable from Hoechst AG under the trade name Hostamont TP ARR 504, sothat a mixing percentage of 1.75% of maleic acid anhydride is containedin the mixture. This mixture is processed into filament thread in theextrusion/spinning facility at 235° C.

EXAMPLES 5 to 8

Granulate mixtures as described in examples 1 and 2, but provided withone each additional adjuvant in a concentration of 0.5 to 1 g/kggranulate mixture, are processed into filament threads at thetemperatures mentioned in the named examples. The mentioned adjuvant is,in turn, a mixture consisting of low molecular polypropylene and 7.5% byweight of 2,5-di-methyl-2,5-bis(t.-butylperoxy-hexane).

EXAMPLES 9 to 12

Granulate mixtures as described in examples 5-8, except that they areemployed pyro-mellitic acid dianhydride is replaced by caprolactum, areprocessed into filament threads at temperatures of 265° C.

EXAMPLES 13 to 15

Granulate mixtures from Example 1 described CR-polypropylene granulateand a self-prepared master batch consisting of the sameCR-polypropylene, commercial polyamide PA 12-granulate and a peroxidicadjuvant as described in examples 5 to 8, the latter in a concentrationof 1 g/kg master batch and another 1 g of the named peroxidic adjuvantper kilo of finished granulate mixture, are mixed in the appropriateproportions, so that the mixture contains a percentage of 0.5; 1 or 3%PA12 by weight. These mixtures are processed into filament thread at265° C.

The most important manufacturing parameters as well as the relevantmechanical properties of the unstretch and the stretch filament threadsare summarized in Table 1 below:

TABLE 1 Example 1 2 3 4 5 Spin Velocity (m/min) 300 300 300 300 300Addition (%) PMSA 0.5 1 3 0.5 MA 1.75 CL PA12 Peroxidic addition (%) 0 00 0 0.5 Tear Resistance, unstretch 10.2 10 9.1 9.5 9.3 [cN/tex] BreakingElongation, 574 636 618 483 674 unstretch (%) Titer unstretched [dtex]436 543 556 379 674 A-module unstretch 52 78 83 49 62 [cN/tex] TearResistance, stretch 54.9 57.1 51.4 44 63.8 [cN/tex] Breaking elongation,29 29 27 25 23 stretched [%] titer, stretched [dtex] 99 98 100 84 82A-module, stretch [cN/tex] 485 384 346 311 329 Example 6 7 8 9 10 SpinVelocity (m/min) 300 300 300 300 300 Addition (%) PMSA 0.5 1 1 MA CL0.05 0.05 PA12 Peroxidic addition (%) 0.1 0.05 0.1 0.05 0.1 TearResistance, unstretch 9.5 9 8 8.8 8.6 [cN/tex] Breaking Elongation, 648690 677 604 598 unstretch (%) Titer unstretched [dtex] 534 544 545 516549 A-module unstretch 63 64 66 44 46 [cN/tex] Tear Resistance, stretch56.2 63.5 43.7 65.7 58.3 [cN/tex] Breaking elongation, 24 25 24 27 26stretched [%] titer, stretched [dtex] 89 84 97 92 92 A-module, stretch[cN/tex] 339 334 424 377 415 Example 11 12 13 14 15 Spin Velocity(m/min) 300 300 300 300 300 Addition (%) PMSA MA CL 1 1 PA12 0.5 1 3Peroxidic addition (%) 0.5 0.1 0.1 0.1 0.1 Tear Resistance, unstretch9.6 9.4 8.9 8.9 8.6 [cN/tex] Breaking Elongation, 575 579 635 653 679unstretch (%) Titer unstretched [dtex] 545 537 555 554 560 A-moduleunstretch 53 53 52 49 66 [cN/tex] Tear Resistance, stretch 59.9 65.855.2 52.1 59.7 [cN/tex] Breaking elongation, 27 24 26 26 25 stretched[%] titer, stretched [dtex] 99 90 92 95 87 A-module, stretch [cN/tex]478 490 124 233 201

EXAMPLE 16

Knitted fabrics, produced from filament threads of example 4, are dyedin closed dye beaker according to the following program: After immersioninto the bath at 60° C. and a 15 minute stay in the bath, thetemperature is raised to 125° C. over a period of 45 minutes, dyeing atthat temperature for 120 minutes, with subsequent cooling down to 50° C.over a period of 40 minutes. Removed the dyed samples and subject sameto an after-treatment at boiling temperatures for 60 minutes in openbath with 1-2 grams per liter each of a polyglycol ether derivative andsoda. Typically employed dye baths, with a liquor ratio of 1:50 and apH-value between pH2 and pH10 hold, as a rule, 0.1-5% of catoniccoloring agent and contain 5 g/l of an anionic, synergistic tensidemixture.

TABLE 2 Material Dye Concentration pH-value K/S value Example 4 C.I.Basic Blue 5 3% 4 34.66 Example 4 C.I. Basic Blue 5 3% 6 36.69 Example 4C.I. Basic Blue 5 3% 8 40.30 Example 4 C.I. Basic Blue 5 3% 10 38.48

What is claimed:
 1. Method for producing aqueous liquor dyeable modifiedpolypropylene threads, characterized in that a CR-polypropylene suitablefor fiber formation is reacted with a reaction partner to form areaction mixture and the obtained reaction mixture is processed intothreads in an extrusion-spinning facility.
 2. Method according to claim1, characterized in that a difunctional carboxylic acid or acorresponding carboxylic acid derivative is employed as reactionpartner.
 3. Method according to claim 2, characterized in that acarboxylic acid ester, a carboxylic acid anhydride, a carboxylic acidamide, a carboxylic acid imide, a carboxylic acid halogenide or acarboxylic acid nitrile is employed as carboxylic acid anhydride. 4.Method according to claim 3, characterized in that pyromellitic aciddi-anhydride or maleic acid anhydride is employed as carboxylic acidanhydride.
 5. Method according to claim 3, characterized in that apolyamide or caprolactam is employed as carboxylic acid amide.
 6. Methodaccording to claim 1, characterized in that a master batch ofpolypropylene and a difunctional carboxylic acid or a correspondingcarboxylic acid derivative is employed as reaction partner.
 7. Methodaccording to claim 1, characterized in that a reaction partner isemployed in an amount of up to approximately 12% by weight.
 8. Methodaccording to claim 1, characterized in that in addition to the propyleneand the reaction partner, a peroxide adjuvant is used.
 9. Methodaccording to claim 8, characterized in that the peroxidic adjuvant isemployed in an amount of up to approximately 1% by weight.
 10. Methodaccording to claim 1, characterized in that the employedextrusion/spinning facility is equipped with an extruder with dynamicand/or static mixing elements.
 11. Method according to claim 1,characterized in that the mass temperature in the extrusion/spinningfacility amounts to approximately 230 to 300° C.
 12. Method accord toclaim 1 characterized in that the mixing is done by mechanical mode. 13.Polypropylene thread obtainable according to the method of claim
 1. 14.Method for dyeing the polypropylene thread of claim 13 characterized inthat the dyeing is effected with dyeing agents from aqueous liquor. 15.Method according to claim 1, characterized in that a reaction partner isemployed in an amount of up to approximately 3% by weight.
 16. Methodaccording to claim 1, characterized in that a reaction partner isemployed in an amount of up to approximately 1% by weight.
 17. Methodaccording to claim 8, characterized in that the peroxidic adjuvant isemployed in an amount of up to approximately 0.5% by weight.
 18. Methodaccording to claim 8, characterized in that the peroxidic adjuvant isemployed in an amount of up to approximately 0.1% by weight.
 19. Textileshapes comprised of the polypropylene thread produced by the method ofclaim
 1. 20. Method for the dyeing of the textile shapes of claim 19wherein the polypropylene thread is dyed using dyeing agents fromaqueous liquor.